Carapidae can be classified in four ecological groups : pelagic, dermersal, commensal and parasitic. Carapidae display otophysic structures associated with the anterior part of the swim bladder and highly ... [more ▼]

Carapidae can be classified in four ecological groups : pelagic, dermersal, commensal and parasitic. Carapidae display otophysic structures associated with the anterior part of the swim bladder and highly modified labyrinths, which suggest particular acoustic performances. The commensal and parasitic species have the best developed sound-producing features and also the thickest sagitta within the largest otic cavity, and surrounded by the thinnest cranial wall. However, these features do not necessarily imply a direct relation between the sound emission and reception in a given species but suggest a selective pressure lying in the habitat use of the species. The structures involved in sound-production and hearing are seemingly adapted to match the loss of energy of the sonic vibrations when travelling through the host tissues. [less ▲]

Carapid species are characterized by so-called otophysical structures (sonic muscles, broad first apophyses covering the anterior part of the swimbladder, etc.) The family includes pelagic (Pyramodon and ... [more ▼]

Carapid species are characterized by so-called otophysical structures (sonic muscles, broad first apophyses covering the anterior part of the swimbladder, etc.) The family includes pelagic (Pyramodon and Snyderidia) and benthic (Echiodon) species and ones that are either commensal with (Onuxodon, Carapus) or parasites of (Encheliophis) invertebrates (sea cucumbers, etc). The aim of the present work was to seek possible relationships between the structures of the inner ear (particularly the sagitta) on the one hand and otophysical structures and lifestyles within the Carapidae family. In the eight species studied, the otic cavity is wide, the saccular otosac and its sagitta are particularly developed. The sacculi touch each other on the median line. A comparison of the inner ear structures reveals notably that the species with the most developed sagitta and sacculus are those with the largest parapophyses and have a commensal or parasitic lifestyle. [less ▲]

Onuxodon fowleri and Encheliophis dubius are two Carapidae species that live in bivalve hosts and, their diet is made of the same type of prey. The aim of this study is to compare their cephalic ... [more ▼]

Onuxodon fowleri and Encheliophis dubius are two Carapidae species that live in bivalve hosts and, their diet is made of the same type of prey. The aim of this study is to compare their cephalic morphology to see whether 1) the head anatomy of both species is related to the constraints of their way of life, and 2) there are difference between these species and commensal carapids that shelter in other invertebrates. The components of their skeletons and muscles are similar, but differ in size and are arranged differently. In O. fowleri, the buccal cavity is smaller than in E. dubius, the jaws (bearing very large anterior teeth) are larger, the quadrato-mandibular joint lies further to the rear, the fibres of muscle bundles A3a, A2a and A2b are more vertical and insert higher on the neurocranium. The buccal system of O. fowleri appears better suited for ingesting food by biting and grasping. That of E. dubius seems better adapted to a feeding mechanism where sucking would have a more important role. The E. dubius head morphology is more similar to the cephalic anatomy of non-bivalve commensal species than to O. fowleri features. Diet constraints may have greater influence than the different host constraints on the head construction. A simulated backward rotation of the posterior part of the E. dubius suspensorium around the posterior joint between the hyomandibular and the neurocranium brings the jaws and the cheeks to coincide with those of O. fowleri. This model could be indicative of how structure modifications and their influences on annex pieces could in part have a role in the biodiversity. [less ▲]

In teleosts, feeding is effected principally by suction and food is handled by the branchial basket. Preys are carried to the oesophagus by the pharyngeal jaws (PJs). The pharyngobranchial bones ... [more ▼]

In teleosts, feeding is effected principally by suction and food is handled by the branchial basket. Preys are carried to the oesophagus by the pharyngeal jaws (PJs). The pharyngobranchial bones constitute the upper pharyngeal jaws (UPJs) and the 5th ceratobranchial bones, the lower pharyngeal jaws (LPJs). In lower teleosts, these jaws have well-separated spindly parts attached to the neurocranium, pectoral girdle, and hyoid bar; they only transport food and LPJ activity predominates. In acanthopterygians, the PJs become stronger, the left and right ceratobranchials fuse into one LPJ, and the pharyngobranchials join together to form two big UPJs articulating with the neurocranium. In labrids and scarids, the LPJ is also joined to the pectoral girdle. In acanthopterygians, a new retractor dorsalis muscle gives the UPJs the major role in food chewing and transport. Cypriniforms have developed original PJs with strong 5th ceratobranchials opposed to a postero-ventral neurocranial plate. Small-sized preys and food particles are seized by the gill rakers, small skeletal pieces supported by the branchial arches. [less ▲]

Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal ... [more ▼]

Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup (Snyderidia canina and Onuxodon fowleri). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle-related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation. This methodology enabled us to separate commensals from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator-type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. We propose changes in both generic diagnoses and transfer three species from Encheliophis to Carapus. [less ▲]

A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraborensis, Encheliophis homei, Encheliophis gracilis and Carapus acus) has ... [more ▼]

A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraborensis, Encheliophis homei, Encheliophis gracilis and Carapus acus) has undertaken to compare it with the diet related characters. The cephalic organization of E. boraborensis and E. gracilis seems related to diet (mainly fishes and shrimps for the first one and holothurian tissues for the other) : these fishes are respectively commensal and parasitic. Although the feeding characters of E. homei and C. acus are closely similar to those of E. boraborensis, there are sparse observations of holothurian tissues in their stomach contents. It is suggested that these fishes are commensal when they are adults and have parasitic tendency when they are juvenile. [less ▲]